Liquid fuel injection pumping apparatus

ABSTRACT

A fuel injection pumping apparatus for an internal combustion engine includes a piston movable under the action of a fluid pressure which varies in accordance with the speed at which the apparatus is driven. The piston controls the maximum amount of fuel which can be fed to the engine by acting as a stop for a shuttle piston. A spring is provided to load the piston against the action of fuel pressure and a resilient seal is provided to engage the end of the piston subjected to the fluid pressure to initially shield a portion of the piston from the fluid pressure. In this manner a higher initial value of fluid pressure is required to effect initial movement of the piston.

Waite States Patent emp et al.

[ Sept. 11, 1973 LIQUID FUEL INJECTION PUMPING APPARATUS [75] Inventors:Kenneth Albert Walters Kemp;

Stanislaw Jan Antoni Sosnowski, both of Ealing, London, England [73]Assignee: C.A.V. Limited, Birmingham,

England [22] Filed: Aug. 31, 1971 [21] Appl. No.: 176,607

[5 1] Int. Cl. F04b 29/00 [58] Field of Search 417/462, 253;

[56] References Cited UNITED STATES PATENTS 3,498,226 3/1970 Mowbray417/253 2,955,578 l0/1960 Flessate et a1. 92/108 2,882,861 4/1959Hillman 92/108 3,433,160 3/1969 Kemp 417/253 Primary ExaminerWilliam L.Freeh Assistant Examiner-Gregory LaPointe Attorneyl-lolman & Stern [5 7]ABSTRACT A fuel injection pumping apparatus for an internal combustionengine includes a piston movable under the action of a fluid pressurewhich varies in accordance with the speed at which the apparatus isdriven. The piston controls the maximum amount of fuel which can be fedto the engine by acting as a stop for a shuttle piston. A spring isprovided to load the piston against the action of fuel pressure and aresilient seal is provided to engage the end of the piston subjected tothe fluid pressure to initially shield a portion of the piston from thefluid pressure. In this manner a higher initial value,

of fluid pressure is required to effect initial movement of the piston.

2 Claims, 3 Drawing Figures PATENTEDSEPI 1 I973 SHEET 1 OF 2 M MM/m 44Maw/6 ATTORNEYS and LIQUID FUEL INJECTION PUMPING APPARATUS Thisinvention relates to liquid fuel injection pumping apparatus of the kindcomprising in combination, an injection pump for delivering fuel intimed relation to an associated engine, a feed pump for supplying fuelto the injection pump, valve means for providing fuel under pressure ata value which varies in accordance with the speed at which the apparatusis driven, a metering shuttle the excursion of which in a cylinderdetermines the maximum quantity of fuel which can be supplied to theinjection pump and a resiliently loaded piston which acts as a stop todetermine the extent of movement of the metering shuttle, the pistonmounting a cam profile which is shaped so that at one extreme positionof the piston as determined by the resilient loading of the spring, themetering shuttle is allowed to move to anrextent such that an excess offuel is provided for starting purposes, the piston being subjected atone end to said fuel under pressure so that as the speed at which theapparatus is driven increases, the piston moves against the action ofthe resilient loading to reduce the excursion of the shuttle.

With such apparatus it is desirable to maintain the supply of excessfuel to the engine when starting the engine, until the engine speed hasattained a value which is above the normal idling speed of the engine.However, it is essential that once this value of speed has been attainedthe engine can idle without excess fuel being provided.

The object of the invention is to provide such an apparatus in a form inwhich the above desiderata are achieved.

According to the invention in an apparatus of the kind specified thecylinder in which the piston is mounted is provided at its endadjacentsaid one end of the piston with a seal member, the seal member when thepiston is at its extreme position masking a portion of said one end ofthe piston to prevent the fuel pressure. acting thereon, thearrangement'being that the fuel pressure must build up to ahigher valuetoeffect I initial movement of'the piston away from the seal member. I

g In the'accompanying drawings:

FIG. 1 is a section through a part of an apparatus in accordance withthe invention, r

. FIG. 2 is a part'se'ction on theline A-A of FIG. 1,

' FIG. 3 is a view similar to FIG. l showing the parts of apparatus inan alternative position.

Referring to. the drawings the apparatus includes a body portion 10inwhich is mounted a rotary cylindrical distributor member 11. The fluidis directed to and discharged from the rotary cylindrical distributorvia a pump of the type disclosed in my previously issued US. Pat. No.3,433,l60. The distributor member is arranged to be driven in timedrelationship with an associated engine. Formed within the distributormember is an axially extending passage 12 which at one end communicateswith an injection pump 9 and which at another point, communicates with adelivery passage 8 which extends to the periphery of the distributormember. The delivery pas'sageis arranged to register with livery passageand an outlet port occurs whilst the injection pump is delivering fuelunder pressure.

Also mounted upon the distributor member is the rotary part of a vanetype feed pump 6 and accommodated within the apparatus is a controlvalve 5 the operation of which results in the supply of fuel underpressure to a passage 13 formed in the body part 10. The action of thevalve is to ensure that the fuel pressure within the passage 13 variesin accordance with the speed at which the-apparatus is driven.

The feed pump is arranged to supply fuel to the injection pump duringthe filling periods of the latter but in order to control the maximumquantity of fuel which can be fed to the injection pump a meteringshuttle arrangement is provided. Again referring to the drawings thereis formed in the body part 10 a cylinder 14 the inner end of whichterminates in a port 15 opening onto the periphery of the distributormember. The port 15 can communicate alternately with two series oflongitudinal grooves 16, 17 formed in the periphery of the distributormember and communicating respectively with circumferential grooves 18,19. Groove 18 communicates with the passage 12 by way. of a non-returnvalve (not shown) and groove 19 communicates with the outlet of the feedpump by way of a throttle device 4. The outer end of the cylinder 14communicates with a pair of ports 20, 21' opening ontothe periphery ofthe distributor member and the port 20 can communicate with each in turnof a plurality of longitudinal grooves 22 which extend from acircumferential groove 23. This latter groove is in constantcommunication with the outlet of the feed pump 6. The port 21 cancommunicatein turn with longitudinal grooves 24 formed on the peripheryof the distributor member and these open into the interior of theapparatus.

Located within the cylinder 14 is a metering shuttle 25 andthearrangement is such that when the port 20 registers with a groove 22fuel will be supplied to the outer end of the cylinder 14 and theshuttle 25 displaced towards the distributor member. During thismovement fuel flows from the port 15 through one of the grooves 16, thecircumferential groove 18 to the ter is delivering fuel to theassociated enginea groove each in turno f a plurality of outlet ports 7which'are connected tothe injection nozzles respectively of theassociated engine. The communication between the de- 17 moves intoregister with the port 15 and a groove 24 moves into register wth theport 21. .When this occurs fuel flows to the inner end of the'cylinder14 and the shuttle 25 is moved outwardly. f

In order to control the maximum quantity of fuel which is supplied tothe injection pump, the excursion of the shuttle is limited by anadjustable stop. This takes the form of a piston 26 which is slidablewithin a cylin der. 27. An intermediate portion of the piston 26 isshaped at 28 to define a cam surface against which a projection 29 onthe shuttle can bear to limit the extent of movement of the shuttle. Thepiston 26 is restrained from angular movement within the cylinder 27 bymeans of a guide member 30 which extends withina cavity formed in thepiston. The angular position of the guide member 30 is adjustable sothat the angular position of the piston can be varied. Moreover, the camsurface 28 is eccentrically dispsosed about the axis of the piston sothat an initial setting of the cam surface can be effected. i

The piston 26 is loaded towards one end of the cylinder 27 by means ofcoiled compression springs 31 and the passage 13 opens into the sidewall of the other end of the cylinder. When the piston 26 is at itsextreme position under the action of the spring 31 the shuttle 25 canpartake of a stroke such that an excess of fuel is provided for startingpurposes. When the engine starts however fuel under pressure is appliedto the piston and the latter is moved against the action of the springs31.

in order to delay the movement of the piston 26 the end wall of thecylinder 27 remote from the springs 31 mounts an-annular resilient sealmember 32 which is contacted by the piston 26 in the extreme positionthereof. The seal member 32 has the effect of preventing fuel underpressure acting upon a substantial portion in this case the centralportion of the end face of the piston. The fuel pressure must thereforerise appreciably before the piston 26 moves against the action of itsspring. Once it has moved however the whole end surface of the piston isexposed to the fuel pressure and the result is that excess fuel issupplied to the engine when starting until a value of speed is reachedwhich is above the normal idling speed of the engine. However, afterthis speed has been reached the engine can be returned to idling speedwithout excess'fuel being se lected.

Since the provision of excess fuel will not be necessary at all timeswhen starting the engine a manually operable release member 33is-provided. As shown in FIG. 1 the member is in a position to engagethe end of the piston thereby to prevent the latter moving to itsextreme position under the action of the springs 31. The member 33 isangularly movable to a position as shown in FIG. 3, in which the pistoncan move its maximum extent under the action of the springs, intocontact with the seal member 32. The member 33 is coupled to a member 34movable from the exterior of the casing, through the intermediary of acoiled torsion spring 35 which allows the manually operable member 33 toreturn to the non-excess fuel position without undue force being exertedupon the piston by the member 33.

We claim:

l. A liquid fuel injection pumping apparatus comprising an injectionpump for delivering fuel in timed rela tion to an associated engine'said fuel injection pump,

comprising an inlet port, at least one outlet port and at least oneworking member adapted to move to draw fluid into and discharge fluidfrom a working chamber forward in part by said working member, a feedpump having an outlet for supplying fuel to the injection pump, valvemeans for controlling the output pressure of said feed pump so that itvaries in accordance with the speed at which the apparatus is driven, ametering shuttle the excursion of which in a cylinder determines themaximum quantity of fuel which can be supplied to the injection pump, afurther cylinder, a piston mounted in said further cylinder resilientmeans loading said piston to one end of said further cylinder, conduitmeans communicating said one end of the cylinder with the outlet of thefeed pump, said piston acting as a stop to determine the extent ofmovement of the metering shuttle, a cam profile formed on said camprofile being shaped so that at one extreme position as determined bythe resilient means, the metering shuttle is allowed to move to anextent such that an excess of fuel is supplied for starting purposes,the piston being subject at one end to fuel under pressure from theoutlet of the feed pump so that as the speed at which the apparatus isdriven increases, the piston will move against the action of theresilient means to reduce the excursion of the shuttle, an annular sealmember positioned in said end of the further cylinder in which thepiston is mounted, the seal member when the piston is at said oneextreme position masking a portion of said one end of the pistion toprevent the fuel pressure acting thereon, and latch means for preventingsaid piston moving to said one extreme position, said latch meansbeing-releasable to permit movement of the piston to said one extremeposition in the absence of fuel pressure acting on said piston, thearrangement being such that when the piston is in said extreme positionthe fuel pressure must attain a higher value to effect initial movementof the piston away from the seal member.

2. A pumping apparatus as claimed in claim 1 in which said latch meanscomprises a pair of relatively movable members one of which is operablefrom the exterior of the apparatus, the other member being positioned tocontact said piston to prevent the piston moving to said one extremeposition, resilient means coupling the pair of members together wherebysaid other member may be moved out of engagement with the piston byoperation of said one member.

x e k 1 w

1. A liquid fuel injection pumping apparatus comprising an injectionpump for delivering fuel in timed relation to an associated engine saidfuel injection pump comprising an inlet port, at least one outlet portand at least one working member adapted to move to draw fluid into anddischarge fluid from a working chamber forward in part by said workingmember, a feed pump having an outlet for supplying fuel to the injectionpump, valve means for controlling the output pressure of said feed pumpso that it varies in accordance with the speed at which the apparatus isdriven, a metering shuttle the excursion of which in a cylinderdetermines the maximum quantity of fuel which can be supplied to theinjection pump, a further cylinder, a piston mounted in said furthercylinder resilient means loading said piston to one end of said furthercylinder, conduit means communicating said one end of the cylinder withthe outlet of the feed pump, said piston acting as a stop to determinethe extent of movement of the metering shuttle, a cam profile formed onsaid cam profile being shaped so that at one extreme position asdetermined by the resilient means, the metering shuttle is allowed tomove to an extent such that an excess of fuel is supplied for startingpurposes, the piston being subject at one end to fuel under pressurefrom the outlet of the feed pump so that as the speed at which theapparatus is driven increases, the piston will move against the actionof the resilient means to reduce the excursion of the shuttle, anannular seal member positioned in said end of the further cylinder inwhich the piston is mounted, the seal member when the piston is at saidone extreme position masking a portion of said one end of the pistion toprevent the fuel pressure acting thereon, and latch means for preventingsaid piston moving to said one extrEme position, said latch means beingreleasable to permit movement of the piston to said one extreme positionin the absence of fuel pressure acting on said piston, the arrangementbeing such that when the piston is in said extreme position the fuelpressure must attain a higher value to effect initial movement of thepiston away from the seal member.
 2. A pumping apparatus as claimed inclaim 1 in which said latch means comprises a pair of relatively movablemembers one of which is operable from the exterior of the apparatus, theother member being positioned to contact said piston to prevent thepiston moving to said one extreme position, resilient means coupling thepair of members together whereby said other member may be moved out ofengagement with the piston by operation of said one member.